A laser beam shines along the surface of a block of transparent material (see $\textbf{Fig. E33.8}$). Half of the beam goes straight to a detector, while the other half travels through the block and then hits the detector. The time delay between the arrival of the two light beams at the detector is 6.25 ns. What is the index of refraction of this material?

## Discussion

## Video Transcript

the refractive index off the quartz begin by the speed of light in the vacuum or their velocity off light inside. That medium speed off light is we know is ah three point old times 10 to the gate into the eight meters per second and over us b which is given here we have 1.94 Dienst end to the power ate it ended power eight meter. So this gives us a refractor. Next off reports, which is 1.54 This is spot A Barbie. We are asked to find What is Linda nods the rev Lint inside the quartz which, um, this is not the welland inside the quartz. Rather, it's the prevalent off the light in video air. So let me distract Lemon Dolly. So Lamda is equal toe end times. Let the Lord story is equal to early guys. Linda, that is equal to 1.5 for affecting if we got here this times. Um, so if the light travels through air, what easy. It's rebelling. So then, um, we have the prevalent will be given by reflecting next time's the prevalent off light inside the quartz, which is 3.55 10 to the power minus seven meters. And this gives us the welland which is 5.47 times 10 to the power into the power minus seven meters. End off the problem. Thank you for

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